ISOLATED HYDROGEN MOLECULES IN GAAS

Molecular hydrogen was directly observed in crystalline GaAs by Raman spectroscopy. At T = 77 K, GaAs samples that have been exposed to a hy drogen/deuterium plasma exhibit four vibrational lines at 2842.6, 3446 .5, 3925.9, and 3934.1 cm(-1), respectively. With a pure hydrogen plas ma only the two high frequency lines can be seen and with a pure deute rium plasma only the lowest frequency is observed. We attribute these frequencies to the rovibrational modes of isolated interstitial D-2, H D, and H-2 molecules, respectively.